The present invention relates to a multi-pack container assembly and, in particular, to a multi-pack container assembly having breakaway tear areas between adjacent containers to facilitate removal of each container from the container assembly. More particularly, the present invention relates to an injection-molded multi-pack container assembly.
Multi-pack container assemblies for storing several separate items are known. Individual servings of food, such as yogurt and pudding, nursery stock, or many other products can be packaged individually. These multi-pack container assemblies typically include several containers that are joined together to form a pack of individually sealed servings. Consumers will know that each container can be separated from the multi-pack so that items in the containers can be used.
Typically, conventional multi-pack container assemblies are made by thermoforming polystyrene. The "form, fill, and seal" machinery needed to make thermoformed polystyrene multi-pack containers is expensive. In addition, the container thermoforming process produces excess scrap polystyrene material. These scraps of material must be collected and disposed of, which is wasteful. Generation of this scrap thus adds cost to the manufacturing of polystyrene thermoformed multi-pack containers. Another problem associated with the use of polystyrene in thermoforming processes is that not many facilities are currently set up to recycle polystyrene. There is also a cost associated with reclaiming scrap material that can be recycled if a recyclable material is used in the manufacture of a thermoformed multi-pack container assembly.
A further disadvantage of multi-pack containers thermoformed from polystyrene is that polystyrene is a brittle material. The brittleness of polystyrene causes it to fracture at unintended spots on the container during separation of the container from the multi-pack, causing the contents of the container to be spilled from the fractured container. This has the disadvantage of both wasting the product and causing an unwelcome mess that must be cleaned up.
It is also known to use cardboard to bundle several separate containers made of plastics material, such as polypropylene, together to provide a multi-pack container assembly. The manufacturing process used to produce cardboard-bundled individual polypropylene containers is expensive. Material costs are higher because cardboard must be used in addition to plastics material. Assembly costs are higher because separate cardboard-handling machinery is needed to bundle the individual containers together.
Another disadvantage of cardboard-bundled polypropylene containers is that a consumer must tear through the cardboard in order to get a container which separates the containers from one another. Once separated, containers are no longer stored as easily as when bundled.
An improved multi-pack container assembly would benefit consumers and also enable dairy processors to enter into the multi-pack yogurt market. Currently, to enter the market a food processor must either purchase a very expensive form, fill, and seal machine which produces a polystyrene, thermoformed package or use cardboard to unite individual containers to form a multi-pack. An improved multi-pack container assembly made of recyclable plastics material using an injection-molding process would solve recycling problems associated with thermoforming polystyrene and would enable a food producer or other packager to enter into the multi-pack market without a large capital investment or high operational and raw material costs.
Accordingly, the present invention provides an injection-molded multi-pack container. The multi-pack container includes a number of individual containers that are joined together by a web. The individual containers each include a skirt, a downwardly extending body, and a stack shoulder joined between the skirt and downwardly extending body. The skirt is located adjacent an opening into cavities in the bodies in which a product is contained. The web includes a tear area between containers that allows individual containers to be removed from the multi-pack.
In preferred embodiments, the multi-pack container is made of high-density polyethylene and includes frangible or breakable ribs that traverse the channels of the tear area of the web. These frangible ribs provide strength reinforcement to the web to reduce the likelihood of inadvertent separation of a container from the multi-pack. The frangible ribs each include a weakened portion that facilitates breaking of the ribs when a consumer desires to remove a container from the multi-pack.
The tear area is defined by an array or matrix of intersecting channels formed in the web. These channels are formed primarily on the back side of the web which is adjacent the downwardly extending bodies which define the containers and are appended to the back side of the web. The "tear area" channels are formed so that they have varying thicknesses at different points along the web. The portion of the channels in the vicinity of the ribs is made thinner so as to aid in the removal of a container from a multi-pack. Thinning the channel in the area of the ribs lessens the likelihood of tearing the stack shoulders or body portions of the containers during removal from the multi-pack.
The tear area channels are also thinned out in the areas where they intersect and join four adjacent containers to the multi-pack. This thinning allows a consumer to tear the web portion joining the four adjacent containers more easily.
Stack shoulders are formed on each container to limit the depth of insertion of one multi-pack container assembly into another underlying multi-pack container assembly. Limitation of the depth of insertion of multi-pack container assemblies into one another during stacking or nesting of such assemblies helps reduce the formation of vacuum between nested or stacked multi-pack containers. Reduction in the formation of vacuum allows nested multi-pack containers to be separated more easily.
Illustratively, a weld bead is formed on an outer lip surrounding the top opening of each individual container. Each weld bead is generally rectangular and includes a substantially flat top. The weld bead functions to thermally isolate the tear area of the web in order to reduce thermal deformation of the tear area when the foodreceiving cavities in the containers are covered by foil and thermally sealed using a heated foil-engaging mandrel. In addition, the weld bead provides a good, flat surface for uniform sealing of the containers using such means as a perforated foil.
The injection-molded polyethylene multi-pack container assembly of the present invention is well-suited for consumer use. Expensive thermoform machinery is not needed to construct the polyethylene injection-molded multi-pack container assembly. In addition, little scrap material is generated during the formation of the multi-pack container assembly of the present invention. In addition, injection-molded polyethylene is less brittle than thermoformed polystyrene and thus will not tear as easily in unintended areas and spill product when an individual container is separated from a multi-pack. This helps reduce product wastage and spillage clean-up. Furthermore, high-density polyethylene (HDPE) is the most desirable material to recycle. Many facilities are currently set up to recycle polyethylene.
The injection-molded polyethylene multi-pack container assembly of the present invention is also believed to be less expensive to manufacture than individual injection-molded containers that are bundled together with cardboard. In addition, the injection-molded polyethylene multi-pack container assembly of the present invention is not destroyed or damaged by the removal of a single container as with bundled polypropylene containers. This allows the multi-pack container assembly of the present invention to continue to provide its excellent storage advantages.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.